In most power driven rotary tools, such as grinding wheels and the like, there is a driven rotatable shaft which overhangs its general support frame which is adapted for tool attachment. The overhanging or protruding shaft, when doing work upon a workpiece, has a propensity for undesired vibration which can produce chatter marks upon a metal workpiece.
There are two types of vibration which the power driven rotary shaft can experience. The first one is from vibration from contact with the workpiece and the second type being self-induced vibrations from the power tool itself. Usually, a power driven rotary tool will support a driven rotary shaft by at least a pair of spaced antifriction bearings, one of the antifriction bearings being at the forward end of the housing near the workpiece and the second antifriction bearing spaced rearwardly from the first antifriction bearing a sufficient distance to provide rigid support for the rotary shaft.
When supported by a pair of such antifriction bearings, a bearing spacer ring is normally used to keep the bearings or the races of the bearings from moving axially along the shaft.
It would be desirable in power driven rotary tools, where the space has already been provided in their construction, for a cylindrical bearing spacer means to substitute a vibration dampening mechanism to improve the finished quality desired on a workpiece.
In many tools, the space is probably available to make a direct substitution with a device according to the present invention.
Patents related in subject matter to that of the present invention are known by the applicant. Specifically, U.S. Pat. No. 3,164,041 to Carlstedt, U.S. Pat. No. 3,207,009 to Carlstedt, and U.S. Pat. No. 3,207,014 to Carlstedt evidence the best knowledge of the prior art known to applicant.